# Practice English Speaking&Listening with: Bar Charts and Pie Charts in R | R Tutorial 2.1 | MarinStatsLectures

Normal
(0)
Difficulty: 0

Hi! I am Mike Marin and in this video we'll talk about producing "bar charts" and "pie charts"

using R. bar charts and pie charts

are appropriate for summarizing the distribution of a categorical variable.

we will be working with the lung capacity data

that was introduced earlier in this series of videos. I've already gone ahead

and imported the data into R and attached it. first

let's discuss the "bar chart": this can be produced

using the "barplot" command. you can access the Help menu

by typing "help" and in brackets inserting the name of the command you'd like help for

or by simply throwing a question mark (?) in front of the name of the command

before producing the bar chart

let's remind ourselves that a bar chart is a visual display

of the frequency for each category of a categorical variable

or the relative frequency or percentage for each category

the frequency table

can be produced using the "table" command in R

let's go ahead and make the frequency table

for the variable Gender;

here we can see that we have 358 females

and 367 males in our sample. let's go ahead

and store this in an object called "count" for use later

we can see the table

is now stored in this object "count". we may also wish to express the bar plot

using relative frequencies or percentages (%). so let's go ahead and

calculate these as well

we can see that there are 725

observations in our dataset; we can divide the table

by 725 to have these expressed as percentages (%)

or relative frequencies; we can see

that our sample consists of about 49.4 percent females

50.6 percent males; let's go ahead

and save this in an object called "percent" for use later

now, we can produce the bar chart using the "barplot" command

let's produce it first for our "counts"

or frequencies;

now, let's take a look at this same plot but using the percentages (%)

or relative frequencies.

we can add a title to this plot

using the "main" argument within the plot command

we can also label the

x-axis using the "xlab" argument as well as the y-axis

using the "ylab" argument.

I also like to rotate

the values on the y-axis using the "las" argument and setting this

equal to 1

to change the names or labels appearing under each of the bars

we can use the "names.arg" argument

here we can insert the names we'd like to appear

under each of the bars. We'll go ahead and use "female"

and "male" as the labels.

finally

if you would like the bars to appear horizontally rather than vertically

this can be achieved using the "horiz" argument and setting this

equal to TRUE. we should also make sure to change

our x and y label as these are now going to

appear on opposite axes.

or other things on this plot explore the Help menu in R.

we can produce a "pie chart"

using the "pie" command.

as before, we can add a title using the "main" argument,

if desired, one can also add a box around this plot

using the "box" command.